1. Brief Description Of The Prior Art
Various types of mufflers have heretofore been proposed for use in conjunction with large internal combustion engines for dampening or attenuating the sound made by the hot gases exhausted from the engine as these gases are vented to the atmosphere. In general, such mufflers include tubular elements which have various shapes, and often contain various numbers and configurations of baffles located on the inside of the external tubular member. The baffles are generally for the purpose of causing the gas to flow through a tortuous or circuitous route in passing from the inlet into the muffler to the exit thereof.
Many mufflers include some sort of packing material or sound absorbing material located in the interior of the muffler, or at least in the outer wall thereof, for dampening the sound made by the escaping hot gases which pass through the muffler when the engine to which it is attached is in use. In general, while certain isolated principles of sound attenuation have been recognized and utilized in various types of muffler designs, I believe that an optimum combination of these features has not been achieved, or at least has not worked as effectively as the combination which I have discovered, and which I now bring before the U.S. Patent and Trademark Office for evaluation, and, hopefully, issuance of a patent thereon.
U.S. Pat. No. 937,665 to Walton discloses a muffler which disposes of hot exhaust gases wherein the gas flow within the muffler is divided into two opposing streams by means of which the gases in the two streams are caused to impinge against each other at several points along the path of flow through the muffler. The muffler housing includes a plurality of baffle plates which include opposed nozzles through which the gas flows, and in being so directed by these nozzles, encounters opposing gas streams so that interference results. The baffle plates utilized in the muffler divide it into three substantially equal sized compartments.
Ronan U.S. Pat. No. 702,031 proposes to divide the hot exhaust gases entering the muffler into two opposing streams and these are then caused to impinge against each other and ultimately to escape into the air from one end of the muffler. The muffler is divided into two substantially equi-sized compartments, and the exhaust gases flow out through a volute located approximately in the center of the muffler.
U.S. Pat. No. 1,700,993 to Bernet et al depicts a plurality of concentric, opposing channels developed by partition plates located inside a muffler, with these channels lying in a substantially longitudinal direction. In these channels, the gas streams impinge against each other. Each concentric channel is defined within the muffler by a longitudinally disposed baffle plate. The flow within the muffler is from the outside flow path inwardly to the next radially inner flow path, and so forth, until the energy depleted exhaust gases reach the center of the muffler.
In Jackson U.S. Pat. No. 4,359,134, a sound-suppressor for air and hot gases is depicted in which the muffler or suppressor comprises a pair of aligned branch passages having a common inlet trunk, and having a common outlet trunk and having the appearance of an 0-shaped hollow member with arms projecting from the opposite sides thereof. One of the branch passages in the sound-suppressor contains a flow restricting orifice, and the other of the branch passages is unobstructed.
U.S. Pat. No. 2,229,913 to Blanchard proposes to divide the incoming hot gas flow into two pipes which diverge from each other as they project further inwardly toward the center of the muffler. The hot gases from these two divergent pipes are then re-merged by impinging the gases against each other at a location near the center of the muffler. From this location, the gases pass into the exhaust pipe from the muffler.
Schnell U.S. Pat. No. 1,844,105 describes a muffler in which a shell is filled with sound absorbing material, which can be any porous, sound deadening material, including "sized, crushed mineral matter", "mica", "exfoliated vermiculite", "brown slag", "coke", "pumice", or other porous aggregate material.
Other muffler patents include Rutt U.S. Pat. No. 4,137,993, Janeway U.S. Pat. No. 2,707,525 and U.S. Pat. No. 4,550,799 which locates a sound absorbing material between an inner skin and an outer skin disposed at the radially outer side of the hollow muffler body.
There has been no prior appreciation of which I am aware of the effect of sizing the several axially arranged contiguous chambers within a muffler according to a certain volumetric size ratio or dimensional correspondence, concurrently with the recognition that it is important to properly size the by-pass or pass through tubes or pipes which extend through partitions in the muffler in order to deliver an optimum relative amount of the hot gases from one chamber to the next in order to contribute to sound reduction optimization, along with a minimal interference with efficient engine operation.